By Kim Deok-hyun WASHINGTON, Oct. 8 (Yonhap) -- The long-standing military alliance between South Korea and the U.S. has become even stronger as they are ready to defend against all possible threats from North Korea, including any instability caused by a transition in the North's leadership, officials said Friday.

Wrapping up the 42nd annual Security Consultative Meeting, South Korean Defense Minister Kim Tae-young and his U.S. counterpart Robert Gates also signed a new set of guidelines to strengthen the combined defense posture and outline the direction of their nations' defense relationship.

"This year's SCM talks proved the fact that the South Korea-U.S. alliance would become stronger whenever threats from North Korea grow," Kim told a group of Korean defense journalists after the talks.

"Also, I and Defense Secretary Gates discussed how to deepen and widen the military ties between the two countries, including further development of a future-oriented alliance," Kim said, describing the atmosphere of the talks as "very amiable."

One of the key developments at the meeting, made clear in a joint communique, was that the allies said they would prepare to defend against a potential instability in North Korea at a time when a leadership succession in the North is apparently taking shape.

Kim and Gates received a report that "highlighted that the combined defense posture is capable and ready to 'fight tonight,' and that it is prepared to effectively respond to any provocation, instability or aggression," the communique said.

It was significant because it marked the first inclusion of the word "instability" in the communique, Seoul's military officials said.

North Korea's ailing leader Kim Jong-il last week appointed his youngest son, Kim Jong-un, a four-star general and to key posts in the North's ruling Workers' Party, setting the stage for the son to become the dictator-in-waiting.

With the 68-year-old father thought to be in poor health after suffering a stroke two years ago, experts have speculated the quick elevation of the 20-something son may lead to infighting, which would pose a grave threat to peace on the Korean Peninsula.

Citing speculation that the leadership succession in North Korea may trigger more aggressive behavior following the March sinking of a South Korean warship, the Cheonan, Gates warned against provocations from the North.

"There's a lot of speculation about the circumstances that lay behind the sinking of the Cheonan and whether other provocations may follow, and I think that our meeting today should have reinforced what we've said that provocations will not be tolerated," Gates told reporters.

"And I think it's a good thing at this point of transition of North Korea that our alliance is in fact, as both Minister (Kim) and I have agreed, perhaps the strongest that it has ever been," he added.

Echoing Gates' view, Kim said South Korea and the U.S. agreed to prepare to defend any instability caused by the leadership transition in North Korea.

When asked about the prospects for the hereditary power transfer in North Korea, Kim said, "No one can predict about how the leadership succession would (result). I think we have to closely watch situations in North Korea."

South Korea and the U.S. also agreed to establish a joint military committee to effectively deter threats posed by North Korea's nuclear programs and other weapons of mass destruction.

The Extended Deterrence Policy Committee is designed to share intelligence on and develop specific countermeasures against the North's nuclear and missile programs, said Chang Kwang-il, Seoul's deputy defense minister for policy.

It is the first time the U.S. has created such a military committee with a non-NATO ally, Chang said, comparing it to NATO's Nuclear Planning Group. "The institutionalization of the Extended Deterrence Policy Committee will serve as a cooperation mechanism to enhance the effectiveness of extended deterrence," Chang said. "By doing so, it would not only send a deterrence message to North Korea, but also help ease security fears over North Korea's nuclear programs among our people."

The Seoul-Washington alliance, forged in blood during the 1950-53 Korean War, is facing fundamental changes over the next five years as the two sides delay Seoul's takeover of wartime operational control of its troops until late 2015. "South Korean and U.S. forces are to continue to enhance the combined defense posture prior to and following the transition of wartime operational control, thereby strengthening deterrent capabilities on the Korean Peninsula," defense minister Kim said.

Called the Strategic Alliance 2015, the new plan was developed after President Lee Myung-bak and U.S. President Barack Obama agreed in June to delay the transfer from 2012, responding to security concerns in the South from the sinking of the Cheonan.

South Korea voluntarily put the operational control of its military under the American-led U.N. Command shortly after the Korean War broke out in 1950. In 1994, peacetime control was handed back to South Korea, but wartime control remains in the hands of the top U.S. commander in South Korea, who heads both the UNC and the South Korea-U.S. Combined Forces Command.

About 28,500 U.S. troops are stationed in South Korea, a legacy of the Korean War.